Recovery of alcohols from hydrocarbon oils



phases.

Patented Sept. 16, 1952 ITE ST TE 4 II x I 61037? 1 micovcnx or ALoQiioLs Rom,

HYDROCARBON 'OII JS Salvatore G. Gallo, Roselle; N; J1, I

Standard Oil Development (iompany a jcorpw ration ofDelaware Application December 6, 1947," Serial No.- 790,136

' 3- Claims. (o1.-2'60: 50)" pqundsirom solutionsthereof with hydrocarbon oils. The invention is. particularly applicable to the recovery of higher oxygenated compounds fromcrude oi ls obtained by the catalytic hydro .genationoi carbon oxides. I I I known to the art in Various processes are I I II which a mixture of hydrocarbons and organic oxygen-containing compounds are produced.

.Soineof these processes are the low temperature carbonization of coal, peat and similarmaterials, ,destructive hydrogenation'of coals, woodshales,

etc, Numerous oxidation processes, particularly oxidation of petroleum oil fraction-such asis :describedin Ellis Chemistry of Petroleum Devrivativesvol. l, chapter 36, pages 830to 845,

also- -yield -mixtures of oxygenated compounds and hydrocarbons. This invention is particularly applicable to products obtained from -a process whereby hydrogen and-oxides of carbon are reacted in the presence of a catalysttovproduce synthetic hydrocarbons, water and; nu-

These oxygenated mateconsist of a mixture of alcohols, acids, aldehydes, ketones and esters and are difiicult to separate from thehydrocarbon oil because first, theyare so numerous, secondly they frequently occur} as in-the case of Fischer Tropschfsynthesis, inthe presence of hydrocarbons of substantially-the i-samev boiling range, thirdly, they often form azeotropeswith eachotherand with the hydrocarbon oils.

:Normally when the products of the above-dei scribed-synthesis operation are condensed'and allOWGd'FtO settle the condensate separates into a idifphase system, that is, an upper oil layer comprising substantially hydrocarbons and hydrocarbon-soluble oxygen-containing materials and a lower water phase comprising substantially water and Water-soluble materials. The oxygen-containing organic compounds formed in the synthesis operationrange from very low molecular weight compounds to very high molecular weight compounds and therefore find themselves distributed throughout the' oil phase and the water'phase depending on their solubilities in these respective- In general, it can be said that the bulk of the organic oxygen-containing compounds of one to three carbon atoms will enter the aqueous phase while the bulk of the compounds containing four carbon atoms and more I per molecule will be found in the oil layer, al-' though it should be borne in mind that the separation of materials into their respective phases is oftentimes not cleancut and depends to alarge oxygen-containing overan distribution or ithe ma'terials instheicondensate.

Thematerialsubjected .tolextra'ction, according of aromatics. "In addition; it. contains anywhere up to about 50% v or more. of oxygenacontaining.

materials, particularly of highmolecula'r. weight suchas those set p out .above. In. cases' z wheregthe material is derived a from the. hydrocarbon syn thesis operation, the oil will. have-dissolved n' l it alcohols, acids, aldehydes, ketones and ters. The esters predominateiamong thelhighf I compounds, particularly that Yiraction boiling above l 350. =15; while carbonyl compounds, thatgis, aldehydes and ketones, acids and -alcohols predominate among the oxygen-containing tcompoundsboiling at temperatures up to-aboutBfil) F. Ordinari-ly the amountsof alcoholsandacids ,found decrease with increasing analytical-distillation temperatures due undoubtedly to the... fact that they-undergo .esterification reactions durin such distillation treatments. The oxy en content s of the hydrocarbon oils'resulting. from thelsynthesis operation generally runsvfrom one weight percent toten weight percent. Extraction methods employed for removing oxygenated compounds from oils includeyextraction with water or with various solventsdma'nhydrous or-aqueous conditions; Typicalssolventszare the aliphatic alcohols suchas methanol, ethanol, ;etc.,, the aliphatic ketones such as acetone; methyl ethyl ketoneletc the glycols: particularly butylene 1,g-1yc01-1',3, butylene: Eglycol-2,3 stand propylene glycol, the lower: aliphatic acid s ,;;suc h as acetic; and propionic,--andcother polar organic oxygenated compounds. Aqueoussalt solutions may also beemployed in-the extraction operation, e. g. aqueous solutions of sodiumacetate; v,"Ihe aqueous salt solutions ;may.-,be2 employed: alone; or in conjunction with one of the, solvents-of theetype named. Any organic solvent having a preferential solvent power for the oxygen-containing substances over thehydrocarbon Oils may be em- 1 ployed as the extractant.

1 The general fact has beenrecognized that the extraction of oxygenated compounds from hydrocarbon oils such'as those produced inthehydrocarbon synthesis process, by the" use of the solvents described is rendered difflculvbecause' of the: adverse capacity and selectivity relations of such solvents. Stated more specifically, "such sol Vents which extract the oxygenated compounds I from the hydrocarbon oils with ,a-relativelyihigh degree of selectivity have a correspondingly low capacity which necessitates the use of high sol--' 'vent to oil ratios. Such adverse relationships are 601 apparent. particularly with the aqueous ;-solvents, and particularly with the extraction of theihigher molecular weight oxygenated compoundsr' The extent upon] the J conditions involved'and; he

parafiins,olefins and in someca'ses, smauamonnts use of high solvent to oil ratios is particularly detrimental in the recovery of the oxygenated compounds from the extract phase. The working up of such an extract layer by distillation is difmay be extracted with a much smaller volume of solvent than that employed in the original extraction. The oxygenated compounds are recovered from the resulting extract layer by distilling ficult and cumbersome due to the high latent 5 oif the solvent with the simultaneous recovery of heats of vaporization of the solvents, and the the oxygenated compounds as the distillation exceedingly large amounts of solvent vto be reresidue. moved requiring, of course, large stripping The drawing represents a diagrammatical facilities. sketch of typical apparatus in which the process In connection with the use of aqueous methanol of the invention may be carried out. as an extractant, it has been found that solvent Referring to the drawing, numeral l represents to oil ratios of 8 and 9 to l are necessary to attain an extraction zone into which hydrocarbon oil satisfactory clean-up and selectivity of oxygenrich in organic oxygenated compounds and parated compounds, particularly the higher alcohols ticularly oxygenated compounds of the same in the C's-Cm molecular weight range, from hyboiling range, is led via line 2. Solvent of the ,drocarbon oils containing them. type previously discussed for extraction of the The process of this invention represents an oxygenated compounds enters the extractionzon'e economical and eflicient method of overcoming at a point near the top through line 3. The feed these difliculties in the recovery of the valuable and solvent are allowed to thoroughly mix in oxygenated compounds. This invention is'dicountercurrent flow within the extraction zone rected to the treatment ofthe extract layer proafter which the lean oil from which the bulk of duced byvcontacting the oxygen-compound-conthe oxygenated compounds has been recovered taining oil with a first solvent in the normal exis removed overhead from the extraction zone traction'process. The resulting extract layer is via line 6. Extract rich in oxygenated comcontacted with a small volume of a second solvent pounds is withdrawn through line 4 ata point "preferably a low boiling hydrocarbon and more near the bottom of the extraction zone and led preferably a low boiling aliphatic hydrocarbon to vessel 5 being introduced at a point somerye -arrange, whereby the oxygenated comwhat below exit line 8. Light hydrocarbon such pounds present in the first extract layer are reas n-heptane, enters vessel 5 at the bottom moved from it. The term low boiling as'applied thereof through line 1 and passes countercurrentthe second solvent means low boiling with re- 13' e flow of eXtract; e light hydrocarbon 'spect to the solute, i. e. the material being exremoves the oxygenated compounds from the extracted;- The resulting lean aqueous first solvent tract and the mixture thereof passes overhead may then be recycled for the extraction of addifrom the extraction zone via line 8 to stripper 9. "tional amounts of the oxygen compound-contain- Lean solvent is recovered from the bottom of ves- LingoiL- I sel 5 and recycled via line I0 to solvent feed line 3 -"I'he solutionof the oxygen compounds in the for use in further extraction operations. In the secondsolvent'e. g. a light hydrocarbon may be stripper 9 heat is applied to the mixture of light treated in one of a number of methods to rehydrocarbons and oxygenated compounds and cover the oxygenated compounds. Preferably, 40 the light hydrocarbon distills overhead and is rethe concentrated solution of oxygenated comcyc1edto feed line 1 via line H for further use. pounds in the light hydrocarbon is distilled in a The concentrated oxygenated compounds are res'tripping zone to remove the light hydrocarbon covered as bottoms from the stripper via line [2 leaving behind as a residue the oxygenated comand can be further processed as desired, e. g. seppounds. This procedure eifects'furthereconomies aration into particular compounds such as alin'the recovery of the oxygenated compounds by cohols, ketones, etc. In the event solvent extrac- -virtue of the fact that the light hydrocarbons tion is employed t recover the oxygenated com- .have considerably lower latent heats of vaporizapounds from the light hydrocarbons the stripper tion than the solvent of the type employed. Al- 9 may be employed as an extraction vessel and ternativelypthe solution of the'oxy enated comthe operation is similar to that carried out in pounds in the light hydrocarbon may be treated extraction zone I. with a third solvent or with a second wash of the The following six examples illustrating specific second .solvent. Since the oxygenated comapplications of my invention show the advanpounds in'the light hydrocarbon are' at a much tages which may be thereby obtained. The ex- ;higher concentration than=that in which they 'amp1es set forth below are illustrative only and were presentin-the original hydrocarbon oil, they are not intended as limitations of the inventions.

Recovery of solute from dilute extract layers lpartblend Raflinate-l e en ittit that ...Examples. 7 .1G 2 3 4 5 6 :Soluteu. u; n-Octanol n-octancl n-Octanol n-Decanol n-Decanol n-Dodecanol Solvent-l 80% Propy- Ethyl 55% Ethyl 55% Ethyl 55% Ethyl 81% methanol lene Glycol Alcohol Alcohol Alcohol Alcohol I Solvent-2 benzene benzene n-hexane n-heptane 54Naphtho' n-heptane Weight percent Solute in Extr. Layer-l l. 1.93 l. 62 l. 21 l. 27 5. 9 "Weight Perccnt Solute in ExtnLayer- 2.2 3. 55 3.16 3.28 2.94 15.0 .Percent Cleanup 3 41 66 52 75 68 Distr. Coefi'. (k alcJ 2.16 5. 5 4.1 10.8 7.3 ll

Blends were composed of 20 volume percent (the C5 or Cw alcohol in alkylate bottoms (boiling range l50-300 C.) except n-dodecanol blend which was 25 weight 1 Boiling range 7lll6 G. I Percent of solute removed by So1vent-2lrom Extract Layer-l.

percent in petroleum naphtha (boiling range l552l5 C.)

4 Concentration of alcohol in Raflinatc-Z (in order) 1.02, 0.648, 0.775, 0.303, 0.405, 1.3 weight percent.

Ihe light hydrocarbons suitable for use in this duce a concentration of the desired component extracted; or, where, for various reasons such as stability, heat requirements, prevention of undesirable azetrope formation etc, it becomes necessary to transfer the desired extracted component from the primary solvent to a more advantageous medium. Where the second solvent is employed only for purposes of transfer the requirement that the second solvent be low-boiling may be relaxed somewhat and a solvent of higher boiling range may be employed.

Having thus described and illustrated the invention in a manner such that it may be practiced by those skilled in the art, I claim:

1. A process for the separation of preferentially oil-soluble aliphatic alcohols from a solution thereof in hydrocarbons which comprises ex tracting said solution with an aqueous aliphatic alcohol solvent to form a first extract phase comprising the alcohols physically dissolved in the aqueous solvent and a first rafflnate phase com- Arcmatic hydrocarbons of low boiling prising the hydrocarbons, separating the phases, contacting the first extract phase with a low boilinghydrocarbon whereby the alcohols become separated from the aqueous solvent and concentrate in the low boiling hydrocarbon forming a second extract phase, separating the aqueous solvent from the second extract phase, and removing the low boiling hydrocarbon from the second extract phase.

2. A process according to claim 1 in which the oil soluble aliphatic alcohols are alcohols containing 8 to 18 carbon atoms per molecule and in which the solvent is aqueous methanol.

8. A process according to claim 2 in which one of the oil soluble, aliphatic alcohols is dodecanol, and in which the low boiling hydrocarbon is nheptane.

SALVATORE GAL REFERENCES crrsn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,943,427 Franzen et al Jan. 16, 1934 2,083,125 Scheuble June 8, 1937 2,193,321 Liethe Mar. 12, 1940 2,274,759 Soenken et a1 Mar. 3, 1942 2,457,257 Michael et al Dec. 23, 1928 2,535,752 Burton May 2, 1950 2,571,151 McGrath et al Oct. 13, 1951 OTHER, REFERENCES Naval Tech. Mission, page 90, Aug. 26, 1946. 

1. A PROCESS FOR THE SEPARATION OF PREFERENTIALLY OIL-SOLUBLE ALIPHATIC ALCOHOLS FROM A SOLUTION THEREOF IN HYDROCARBONS WHICH COMPRISES EXTRACTING SAID SOLUTION WITH AN AQUEOUS ALIPHATIC ALCOHOL SOLVENT TO FORM A FIRST EXTRACT PHASE COMPRISING THE ALCOHOLS PHYSICALLY DISSOLVED IN THE AQUEOUS SOLVENT AND A FIRST RAFFINATE PHASE COMPRISING THE HYDROCARBONS, SEPARATING THE PHASES, CONTACTING THE FIRST EXTRACT PHASE WITH A LOW BOILING HYDROCARBON WHEREBY THE ALCOHOLS BECOME SEPARATED FROM THE AQUEOUS SOLVENT AND CONCENTRATE IN THE LOW BOILING HYDROCARBON FORMING A SECOND EXTRACT PHASE, SEPARATING THE AQUEOUS SOLVENT FROM THE SECOND EXTRACT PHASE, AND REMOVING THE LOW BOILING HYDROCARBON FROM THE SECOND EXTRACT PHASE. 